Protection of confidential information may be more difficult than ever before because of the proliferation of networked computing devices. Comprehensive protection of information stored in computer-readable form should include identity management, authorization/authentication, data integrity assurance, proper logging/auditing, i.e., to ensure chain of custody, and a guarantee of confidentiality. Data encryption is part of most protection regimes. Data encryption can be employed for data in-flight and for data at rest. Data in-flight encryption is especially valuable for data that leaves the relatively safer and more secure “behind the firewall” environment. Data in-flight has received significant attention, and there are many commercially available products. Data at rest has received less attention. Recently, there have been some highly publicized incidents in which data at-rest in the form of backups on tapes have been lost or otherwise compromised. This publicity has lead to increased demand for devices that can encrypt data at rest on tape. However, the threat to data at rest may actually be greater when it is stored on disk than on tape. This is because the on-disk data is more current, and therefore more valuable. Further, the data on-disk is more likely to be accessible via a network, and a greater number of individuals are likely to have access to the data, whether rightfully or not.
One vulnerability of known encryption schemes is the “super user problem.” In order to maintain a network and storage system, network administrators and storage administrators are typically provided with unrestricted access to files. Further complicating matters, file servers typically provide a means by which remote users with administrator privileges, a.k.a. “super users,” are granted the equivalent of local administrator access. Since the remote administrator is granted local administrator privileges, that remote administrator can have full and unencumbered access to metadata and data, regardless of defined file or directory ownership and permissions. UNIX and Linux systems have a mechanism by which to treat remote “root” users as if they were local. This capability is also common to dedicated NAS servers. This mechanism also makes it possible for administrators to subvert or circumvent permissions and other access controls. Such access is a significant compromise to confidentiality. However, it is also necessary for the super-users to perform legitimate administrative functions on networked resources, perhaps remotely, so the super user cannot simply be eliminated.